Behaviour/Interactions among Microorganisms/Invertebrates

• behaviour of microbes relates to the ability to control position in environment
• Motility is dependent on having one of the following:

  flagella, Gliding, Swimming appendages, undulating bodies
• Taxis -> movement of organisms in response to stimuli (chemicals, light, magnetism)
• Taxis is required for survival for many organisms as it allows them to leave unsuitable conditions
• how is cyanobacteria a example of taxis?

  they fill/empty vesicles with gas to increase/decrease buoyancy which allows them to control their place in the water column to ensure they have enough nutrients and lights
• chemotaxis is the most common form of taxis
• Trait mediated interactions -> evolved traits in response to selective pressure associated with interaction (prey evolve larger defence structure in response to predation)
• Density mediated interactions -> changes in populations of one species in response to another (predator population increases due to increase in prey)
• consumption of small planktonic cells links microbial loop to macroscopic food wed
• rate of consumption is dependent on?

  [particles], quality of particles, size of particles, temp of environment, particle defense
• What are 4 strategies of ingestion of Microorganisms?

  scrapers, shredders, collector/gathers, filter feeders
• Scrapers

  • scrape biofilms off surfaces
  • are herbivores
• Shredders

  • eat detritus
  • causes them to consume a larger variety of microbes
  • microbes condition detritus and increase nutrient content
  • peanut butter on the cracker
• Collector-Gatherers

  • pick out particles rich in cellular material (eat whole microbial assemblages
• Filter feeders

  • filter microorganisms from water
  • passive vs. active
• Passive filter feeders are organisms that rely on the natural flow of water to passively capture food particles, while active filter feeders actively pump or move water through specialized structures to collect food particles.
• What are three ways that microbes avoid predation

  • indigestibility -> ex. thick mucilage to protect from digestion
  • poor nutritional value/toxin production
  • spines and physical defence
• microbial group results in rapid remineralization of nutrients and carbon